1. Field of the Invention
The field of this invention is that of optical fiber connectors and in particular to the retention of an optical fiber in a terminus.
2. Description of Related Art
Optical fibers commonly are connected by pin and socket type connectors which position the ends of two optical fibers in adjacency so that light can be transmitted from one to the other. This type of connector may take a variety of forms, but will include a pin terminus having a forward end that is received within a socket at the forward end of the socket terminus to align the two connector sections. Frequently, the forward ends of the optical fibers will be in abutment in the mated connector.
In order to minimize light attenuation across the connector, it is essential that the optical fibers be firmly and securely held within the two connector sections. Minor amounts of movement of the optical fibers can result in misalignments which produce unacceptably large optical losses.
A common technique for securing the fibers in the connector bodies is to make use of an adhesive to bond the fibers in position. Although this can result in a secure attachment, it penalizes production rates because of the cure time required for the adhesive. The shelf life of the adhesive is limited which is a factor adding to the cost and complexity of production and which makes field use difficult. Adhesives can be difficult to handle.
Another means of attachment of the optical fiber is to crimp a portion of the connector body inwardly around the fiber to grip the fiber at a contracted zone. The crimping operation must be carefully controlled in order to achieve precisely the desired amount of gripping force. Even so, localized areas of excessive pressure may result which can cause minute localized bending and resulting attenuation of the light signal. Also, when the connector is subjected to temperature extremes, the crimp connection may become either too loose or too tight, again resulting in optical losses.
Another type of optical fiber connector, owned by the same assignee as that of this invention, provides a small grommet of elastomeric material near the forward end of the connector body surrounding the optical fiber. This grommet is compressed by a spring loaded plunger and is intended to grip the fiber to retain it in the connector. However, resulting retention force is relatively small that the fiber is not held as securely as it should be. Also, a spring arrangement is necessary to compensate for temperature fluctuations. This adds to the complexity and weight of the connector.